Trig: suggestion for handling extreme cases

Signed-off-by: Christoph Ruegg <git@cdrnet.ch>

src/Managed.UnitTests/TrigonometryTest.cs

@@ -449,8 +449,8 @@
         [Row(-8.388608e6, 0.0, -1.0, 0.0)]
         [Row(1.19209289550780998537e-7, 0.0, 1.1920928955078043e-7, 0.0)]
         [Row(-1.19209289550780998537e-7, 0.0, -1.1920928955078043e-7, 0.0)]
-        //[Row(8.388608e6, 1.19209289550780998537e-7, 1.0, 0.0)]
-        //[Row(-8.388608e6, -1.19209289550780998537e-7, -1.0, 0.0)]
+        [Row(8.388608e6, 1.19209289550780998537e-7, 1.0, 0.0)]
+        [Row(-8.388608e6, -1.19209289550780998537e-7, -1.0, 0.0)]
         [Row(0.5, -0.5, 0.56408314126749848, -0.40389645531602575)]
         public void CanComputeComplexHyperbolicTangent(double real, double imag, double expectedReal, double expectedImag)
         {
@@ -465,8 +465,8 @@
         [Row(-8.388608e6, 0.0, -1.0, 0.0)]
         [Row(1.19209289550780998537e-7, 0.0, 8388608.0000000574, 0.0)]
         [Row(-1.19209289550780998537e-7, 0.0, -8388608.0000000574, 0.0)]
-//        [Row(8.388608e6, 1.19209289550780998537e-7, 1.0, 0.0)]
-        //[Row(-8.388608e6, -1.19209289550780998537e-7, -1.0, 0.0)]
+        [Row(8.388608e6, 1.19209289550780998537e-7, 1.0, 0.0)]
+        [Row(-8.388608e6, -1.19209289550780998537e-7, -1.0, 0.0)]
         [Row(0.5, -0.5, 1.1719451445243514, -0.8391395790248311)]
         public void CanComputeComplexHyperbolicCotangent(double real, double imag, double expectedReal, double expectedImag)
         {
@@ -481,7 +481,7 @@
         [Row(-8.388608e6, 0.0, 0.0, 0.0)]
         [Row(1.19209289550780998537e-7, 0.0, 0.99999999999999289, 0.0)]
         [Row(-1.19209289550780998537e-7, 0.0, 0.99999999999999289, 0.0)]
-//        [Row(8.388608e6, 1.19209289550780998537e-7, 0.0, 0.0)]
+        [Row(8.388608e6, 1.19209289550780998537e-7, 0.0, 0.0)]
         [Row(-8.388608e6, -1.19209289550780998537e-7, -0.0, 0.0)]
         [Row(0.5, -0.5, 0.94997886761549463, 0.23982763093808804)]
         public void CanComputeComplexHyperbolicSecant(double real, double imag, double expectedReal, double expectedImag)
@@ -497,7 +497,7 @@
         [Row(-8.388608e6, 0.0, 0.0, 0.0)]
         [Row(1.19209289550780998537e-7, 0.0, 8388607.9999999978, 0.0)]
         [Row(-1.19209289550780998537e-7, 0.0, -8388607.9999999978, 0.0)]
-//        [Row(8.388608e6, 1.19209289550780998537e-7, 0.0, 0.0)]
+        [Row(8.388608e6, 1.19209289550780998537e-7, 0.0, 0.0)]
         [Row(-8.388608e6, -1.19209289550780998537e-7, 0.0, 0.0)]
         [Row(0.5, -0.5, 0.91207426403881078, 1.0782296946540223)]
         public void CanComputeComplexHyperbolicCosecant(double real, double imag, double expectedReal, double expectedImag)

src/Managed/Trigonometry.cs

@@ -232,6 +232,12 @@ namespace MathNet.Numerics
             }
 
             var exp = value.Exponential();
+
+            if (exp.IsInfinity)
+            {
+                return Complex.Zero;
+            }
+
             return 2 * exp / (exp.Square() - 1);
         }
 
@@ -314,6 +320,12 @@ namespace MathNet.Numerics
 
             var sini = Sine(value.Imaginary);
             var sinhr = HyperbolicSine(value.Real);
+
+            if (double.IsInfinity(sinhr))
+            {
+                return new Complex(double.IsPositiveInfinity(sinhr) ? 1 : -1, 0.0);
+            }
+
             var denom = (sini * sini) + (sinhr * sinhr);
 
             return new Complex(sinhr * HyperbolicCosine(value.Real) / denom, sini * Cosine(value.Imaginary) / denom);
@@ -350,6 +362,12 @@ namespace MathNet.Numerics
             }
 
             var exp = value.Exponential();
+
+            if (exp.IsInfinity)
+            {
+                return Complex.Zero;
+            }
+
             return 2 * exp / (exp.Square() + 1);
         }
 
@@ -432,6 +450,12 @@ namespace MathNet.Numerics
 
             var cosi = Cosine(value.Imaginary);
             var sinhr = HyperbolicSine(value.Real);
+
+            if (double.IsInfinity(sinhr))
+            {
+                return new Complex(double.IsPositiveInfinity(sinhr) ? 1 : -1, 0.0);
+            }
+
             var denom = (cosi * cosi) + (sinhr * sinhr);
 
             return new Complex(HyperbolicCosine(value.Real) * sinhr / denom, cosi * Sine(value.Imaginary) / denom);